The tree modification log needs two ways to create dummy extent buffers,
once by allocating a fresh one (to rebuild an old root) and once by
cloning an existing one (to make private rewind modifications) to it.
Signed-off-by: Jan Schmidt <list.btrfs@xxxxxxxxxxxxx>
---
fs/btrfs/extent_io.c | 73 +++++++++++++++++++++++++++++++++++++++++++++----
fs/btrfs/extent_io.h | 3 ++
2 files changed, 70 insertions(+), 6 deletions(-)
diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index 2fb52c2..4f4bcaa 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -3967,6 +3967,58 @@ static struct extent_buffer *__alloc_extent_buffer(struct extent_io_tree *tree,
return eb;
}
+struct extent_buffer *btrfs_clone_extent_buffer(struct extent_buffer *src)
+{
+ unsigned long i;
+ struct page *p;
+ struct extent_buffer *new;
+ unsigned long num_pages = num_extent_pages(src->start, src->len);
+
+ new = __alloc_extent_buffer(NULL, src->start, src->len, GFP_ATOMIC);
+ if (new == NULL)
+ return NULL;
+
+ for (i = 0; i < num_pages; i++) {
+ p = alloc_page(GFP_ATOMIC);
+ BUG_ON(!p);
+ attach_extent_buffer_page(new, p);
+ WARN_ON(PageDirty(p));
+ SetPageUptodate(p);
+ new->pages[i] = p;
+ }
+
+ copy_extent_buffer(new, src, 0, 0, src->len);
+ set_bit(EXTENT_BUFFER_UPTODATE, &new->bflags);
+
+ return new;
+}
+
+struct extent_buffer *alloc_dummy_extent_buffer(u64 start, unsigned long len)
+{
+ struct extent_buffer *eb;
+ unsigned long num_pages = num_extent_pages(0, len);
+ unsigned long i;
+
+ eb = __alloc_extent_buffer(NULL, start, len, GFP_ATOMIC);
+ if (!eb)
+ return NULL;
+
+ for (i = 0; i < num_pages; i++) {
+ eb->pages[i] = alloc_page(GFP_ATOMIC);
+ if (!eb->pages[i])
+ goto err;
+ }
+ set_extent_buffer_uptodate(eb);
+ btrfs_set_header_nritems(eb, 0);
+
+ return eb;
+err:
+ for (i--; i > 0; i--)
+ __free_page(eb->pages[i]);
+ __free_extent_buffer(eb);
+ return NULL;
+}
+
static int extent_buffer_under_io(struct extent_buffer *eb)
{
return (atomic_read(&eb->io_pages) ||
@@ -3978,7 +4030,8 @@ static int extent_buffer_under_io(struct extent_buffer *eb)
* Helper for releasing extent buffer page.
*/
static void btrfs_release_extent_buffer_page(struct extent_buffer *eb,
- unsigned long start_idx)
+ unsigned long start_idx,
+ int mapped)
{
unsigned long index;
struct page *page;
@@ -3992,7 +4045,7 @@ static void btrfs_release_extent_buffer_page(struct extent_buffer *eb,
do {
index--;
page = extent_buffer_page(eb, index);
- if (page) {
+ if (page && mapped) {
spin_lock(&page->mapping->private_lock);
/*
* We do this since we'll remove the pages after we've
@@ -4017,6 +4070,8 @@ static void btrfs_release_extent_buffer_page(struct extent_buffer *eb,
}
spin_unlock(&page->mapping->private_lock);
+ }
+ if (page) {
/* One for when we alloced the page */
page_cache_release(page);
}
@@ -4026,12 +4081,18 @@ static void btrfs_release_extent_buffer_page(struct extent_buffer *eb,
/*
* Helper for releasing the extent buffer.
*/
-static inline void btrfs_release_extent_buffer(struct extent_buffer *eb)
+static inline void btrfs_release_extent_buffer(struct extent_buffer *eb,
+ int mapped)
{
- btrfs_release_extent_buffer_page(eb, 0);
+ btrfs_release_extent_buffer_page(eb, 0, mapped);
__free_extent_buffer(eb);
}
+void free_cloned_extent_buffer(struct extent_buffer *eb)
+{
+ btrfs_release_extent_buffer(eb, 0);
+}
+
static void check_buffer_tree_ref(struct extent_buffer *eb)
{
/* the ref bit is tricky. We have to make sure it is set
@@ -4201,7 +4262,7 @@ free_eb:
}
WARN_ON(!atomic_dec_and_test(&eb->refs));
- btrfs_release_extent_buffer(eb);
+ btrfs_release_extent_buffer(eb, 1);
return exists;
}
@@ -4245,7 +4306,7 @@ static void release_extent_buffer(struct extent_buffer *eb, gfp_t mask)
spin_unlock(&tree->buffer_lock);
/* Should be safe to release our pages at this point */
- btrfs_release_extent_buffer_page(eb, 0);
+ btrfs_release_extent_buffer_page(eb, 0, 1);
call_rcu(&eb->rcu_head, btrfs_release_extent_buffer_rcu);
return;
diff --git a/fs/btrfs/extent_io.h b/fs/btrfs/extent_io.h
index b516c3b..80dd65a 100644
--- a/fs/btrfs/extent_io.h
+++ b/fs/btrfs/extent_io.h
@@ -265,6 +265,9 @@ void set_page_extent_mapped(struct page *page);
struct extent_buffer *alloc_extent_buffer(struct extent_io_tree *tree,
u64 start, unsigned long len);
+struct extent_buffer *alloc_dummy_extent_buffer(u64 start, unsigned long len);
+struct extent_buffer *btrfs_clone_extent_buffer(struct extent_buffer *src);
+void free_cloned_extent_buffer(struct extent_buffer *eb);
struct extent_buffer *find_extent_buffer(struct extent_io_tree *tree,
u64 start, unsigned long len);
void free_extent_buffer(struct extent_buffer *eb);
--
1.7.3.4
--
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